Fuel cell interconnect with iron rich rib regions and method of making thereof

Abstract

A method of making an interconnect for a solid oxide fuel cell stack includes providing an iron rich material containing at least 25 wt. % iron into channels of a mold, providing a powder containing 4-6 wt. % Fe, 0-1 wt. % Y and balance Cr into the mold over the iron rich material containing at least 25 wt. % iron, compacting the iron rich material containing at least 25 wt. % iron and the powder comprising 4-6 wt. % Fe, 0-1 wt. % Y and balance Cr in the mold to form the interconnect, and sintering the interconnect to form a sintered interconnect having iron rich regions having an iron concentration greater than 10% in ribs of the interconnect.

What is claimed is: 
     
       1. A method of making an interconnect for a solid oxide fuel cell stack, comprising:
 providing an iron rich material into channels of a mold; 
 providing a powder comprising 4-6 wt. % Fe, 0-1 wt. % Y and balance Cr into the mold over the iron rich material; 
 compacting the iron rich material and the powder comprising 4-6 wt. % Fe, 0-1 wt. % Y and balance Cr in the mold to form the interconnect; and 
 sintering the interconnect to form a sintered interconnect having iron rich regions having an iron concentration greater than 10% in ribs of the interconnect; 
 wherein the step of providing the iron rich material into the channels of the mold comprises providing iron foil strips into the channels of the mold. 
 
     
     
       2. A method of making an interconnect for a solid oxide fuel cell stack, comprising:
 providing an iron rich material into channels of a mold; 
 providing a powder comprising 4-6 wt. % Fe, 0-1 wt. % Y and balance Cr into the mold over the iron rich material; 
 compacting the iron rich material and the powder comprising 4-6 wt. % Fe, 0-1 wt. % Y and balance Cr in the mold to form the interconnect; and 
 sintering the interconnect to form a sintered interconnect having iron rich regions having an iron concentration greater than 10% in ribs of the interconnect; 
 wherein: 
 the step of providing the iron rich material into the channels of the mold comprises providing a powder comprising chromium and at least 25 wt. % iron into the channels of the mold with a first shoe; and 
 the step of providing the powder comprising 4-6 wt. % Fe, 0-1 wt. % Y and balance Cr comprises providing the powder comprising 4-6 wt. % Fe, 0-1 wt. % Y and balance Cr into the mold over the powder comprising chromium and at least 25 wt. % iron with a second shoe. 
 
     
     
       3. A method of making an interconnect for a solid oxide fuel cell stack, comprising:
 providing an iron rich material into channels of a mold; 
 providing a powder comprising 4-6 wt. % Fe, 0-1 wt. % Y and balance Cr into the mold over the iron rich material; 
 compacting the iron rich material and the powder comprising 4-6 wt. % Fe, 0-1 wt. % Y and balance Cr in the mold to form the interconnect; and 
 sintering the interconnect to form a sintered interconnect having iron rich regions having an iron concentration greater than 10% in ribs of the interconnect; 
 wherein: 
 the step of providing the iron rich material into the channels of the mold comprises providing a pure iron powder into the channels of the mold with a first shoe; and 
 the step of providing the powder comprising 4-6 wt. % Fe, 0-1 wt. % Y and balance Cr comprises providing the powder comprising 4-6 wt. % Fe, 0-1 wt. % Y and balance Cr into the mold over the pure iron powder with a second shoe. 
 
     
     
       4. A method of making an interconnect for a solid oxide fuel cell stack, comprising:
 providing a chromium alloy interconnect having ribs separated by channels; and 
 forming metal or metal oxide caps directly on the top surfaces of the ribs on both air and fuel sides of the interconnect but not on bottom of the channels, wherein the metal or metal oxide caps comprise iron, manganese, cobalt, copper, a superalloy or an oxide thereof; 
 wherein the metal or metal oxide caps are located on the top surfaces of the ribs and on sides of the ribs but not on the bottom of the channels. 
 
     
     
       5. A method of making an interconnect for a solid oxide fuel cell stack, comprising:
 providing a chromium alloy interconnect having ribs separated by channels; 
 forming metal or metal oxide caps directly on the top surfaces of the ribs on both air and fuel sides of the interconnect but not on bottom of the channels, wherein the metal or metal oxide caps comprise iron, manganese, cobalt, copper, a superalloy or an oxide thereof; and 
 forming a lanthanum strontium manganite layer, a manganese cobalt oxide layer, or a composite lanthanum strontium manganite/manganese cobalt oxide layer on the metal or metal oxide caps and on the bottom of the channels. 
 
     
     
       6. An interconnect for a solid oxide fuel cell stack, comprising:
 a chromium alloy interconnect having ribs separated by channels; and 
 metal or metal oxide caps located directly on the top surfaces of the ribs on both air and fuel sides of the interconnect but not on bottom of the channels, wherein the metal or metal oxide caps comprise iron, manganese, cobalt, copper, a superalloy or an oxide thereof; 
 wherein the metal or metal oxide caps are located on the top surfaces of the ribs and on sides of the ribs but not on the bottom of the channels. 
 
     
     
       7. The method of  claim 5 , wherein the step of forming the lanthanum strontium manganite layer, the manganese cobalt oxide layer, or the composite lanthanum strontium manganite/manganese cobalt oxide layer comprises forming the lanthanum strontium manganite layer on the metal or metal oxide caps and on the bottom of the channels. 
     
     
       8. The method of  claim 5 , wherein the step of forming the lanthanum strontium manganite layer, the manganese cobalt oxide layer, or the composite lanthanum strontium manganite/manganese cobalt oxide layer comprises forming the manganese cobalt oxide layer on the metal or metal oxide caps and on the bottom of the channels. 
     
     
       9. The method of  claim 5 , wherein the step of forming the lanthanum strontium manganite layer, the manganese cobalt oxide layer, or the composite lanthanum strontium manganite/manganese cobalt oxide layer comprises forming the composite lanthanum strontium manganite/manganese cobalt oxide layer on the metal or metal oxide caps and on the bottom of the channels.